This paper considers a multi-period mean-variance portfolio selection problem with no shorting constraint. We assume that the sample space is finite, and the possible securities price vector transitions is equivalent to the number of securities. By making use of the embedding technique of Li and Ng (2000), the original nonseparable problem can be solved by introducing an auxiliary problem. After the risk neutral probability is calculated, the auxiliary problem can be solved by using the martingale method of Pliska (1986). Finally, we derive a closed form of the optimal solution to the original constrained problem.
In this study, we used Lentinus edodes residues (XG) and Pleurotus ostreatus residues (PG) as compost materials and used a high-temperature static aerobic composting system to examine the effects of different treatment. We analyzed changes in temperature and compost structure during the process of composting. The study showed that XG and PG mixed by 1:1 increased the temperature of the compost pile and reached to the environmental temperature more rapidly. Mix treatment had maximum temperature of 71°C, had longest megathermal period continued about 9 days than other groups. Scanning Electron Microscope (SEM) showed mix treatment had the best lignin structure variation trend while PG had the worst. Thus, mix treatment significantly increased the composting rate, reaching complete decomposition 10 days before other treatments. These data also suggested that XG as a compost material is better that PG.
In order to study the vehicles queuing under traffic accidents, we put the traffic wave analogy into fluid wave, and build traffic wave model, getting the relationship equation: vehicles queue length and the actual capacity of cross-section, accidents duration, section of the upstream traffic. According to analyzing the equation, we get: the maximum queue length increase with upstream traffic as category Index, however, inversely proportional to the actual capacity, and it is positively correlated with the duration of the accident.
By analyzing the relations of the excess air ratio to heat loss due to exhaust gas, chemical incomplete combustion and combustibles in refuse, the traditional method for solving the optimal excess air ratio is improved. A correction factor is proposed for heat loss due to combustibles in refuse, making the solving method more accurate, which is of great importance for improving the combustion efficiency of the boiler.
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